Temperature dependence of the ordering of semiconducting fluorene-thiophene copolymers on rubbed polyimide alignment layers

Lisa R. Pattison; Alexander Hexemer; Edward J. Kramer; Pierre M. Petroff; Daniel A. Fischer

doi:10.1117/12.617868

3 October 2005 Temperature dependence of the ordering of semiconducting fluorene-thiophene copolymers on rubbed polyimide alignment layers

Lisa R. Pattison, Alexander Hexemer, Edward J. Kramer, Pierre M. Petroff, Daniel A. Fischer

Author Affiliations +

Proceedings Volume 5938, Organic Photovoltaics VI; 59380O (2005) https://doi.org/10.1117/12.617868
Event: Optics and Photonics 2005, 2005, San Diego, California, United States

Abstract

There has been great interest in recent years in using solution processible conjugated organic polymers as the active layers in semiconducting devices including field-effect transistors (FETs), light emitting diodes (LEDs), and photovoltaics (PVs). The structure of the polymer film is very important to device performance at the interfaces where charge separation and collection occur, as well as in the bulk of the film, where it has been shown that alignment of the polymer backbone can increase the pi-orbital overlap, thus enhancing charge carrier mobility. In this work, we report on the temperature-dependent alignment of liquid crystalline fluorene-thiophene copolymer thin film surfaces using the near-edge X-ray fine absorption structure (NEXAFS) technique. Partial electron yield spectra were recorded over a range of temperatures to observe directly the bond orientation in various polymer phases. In addition, samples were annealed under varying processing conditions and spectra were taken at room temperature on these heat-treated samples. The NEXAFS data shows: a) in thin polyfluorene films, the polymer backbone lies flat in the plane of the substrate, b) that along the main chain axis, biphenyl and thiophene rings have a preference to lie flat in the plane of the surface, c) the orientation of the polymer backbone can be controlled using a rubbed polyimide alignment layer as a template for liquid crystal orientation, and d) under proper annealing conditions, there is strong temperature-dependent alignment of the copolymer main-chain axis to the rubbing direction with dichroic ratio (R) reaching R=0.7.

Citation Download Citation

Lisa R. Pattison, Alexander Hexemer, Edward J. Kramer, Pierre M. Petroff, and Daniel A. Fischer "Temperature dependence of the ordering of semiconducting fluorene-thiophene copolymers on rubbed polyimide alignment layers", Proc. SPIE 5938, Organic Photovoltaics VI, 59380O (3 October 2005); https://doi.org/10.1117/12.617868

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
8 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Polymers

Molecules

X-rays

Temperature metrology

Absorption

Thin films

Liquid crystals

Show All Keywords

Keywords/Phrases

Search In:

Publication Years